Method of producing a plurality of colored images in a single photographic emulsion layer



Of 9, 1934 M w. SEYMOUR ET Al. 1,976,301-

EHuLsIoH (/U RAw EILMExRosED I Eff- LIGHT sILvERRED-coIoRIHAeE/If FDRHING DEVELOPER.

DHEA sILvER IDDIDE IMAGE coNvERTED m CLEARING BATH "lll, 'l' I, masseeniamnwseaasun EXPOSD FROM m EHuLsIoII sIDE sILvERDeREEH DYE IMAGE at DEvELDPED IAI DYEHsILI/ER IoDIDE'IHAa k coLoR DEVELOPER DYE IMAGE f' .sILvER IMAGE DYEHSILIIHRIDDIDE IMAGE LEAcHED sEcoIID DYE IMAGE iza FIXED FIRST DYE IMAGE mmtou Patented Oct. 1934 UNITED STATES PATENT OFI-ica BIETHOD OF PRODUCING A PLURALITY OF COLORED IMAGES IN A SINGLE PHOTO- GBAPHIC EMULSION LAYER Application November 12, 1931, Serial No. 574,672

` 11 Claims.

This invention relates to color photography, and more particularly to the making of subtractive prints in which more than one colored image is produced in the same emulsion layer.

The invention relates to a method for producing two, three, or even more color images in a single layer, and especially involves a new step which makes such a process successful; and, particularly to a process comprising exposing a positive film through a color component negative, developing the positive image in a developer that gives a colored product, preferably complementary in color to the iilter through which the negative was taken, exposing the positive iilm a second time in register with a second color component negative, developing the second image with a developer that gives a product of a diierent color, preferably complementary in color to the second iilter, and repeating this exposure and development to introduce as many colored images as are necessary. When all the images have been introduced, the developed silver is removed with a reagent that does not attack the colored images, and the remaining silver salts are fixed out.

In practice we have found that each exposure, while it is primarily developed in its own developer, is also susceptible to a certain amount of further development in the succeeding developer. This is detrimental to the successful working of the process, as the purity of the colors is degraded by the further development of any given image to a color different from that intended. We have succeeded inovercoming this detrimental action by submitting thelayer after each development to the action of an oxidizing agent which either removes the developed silver or converts it into a salt of silver which is not susceptible to spontaneous development without eX- posure to light and also destroys any remaining latent image. This oxidizing bath must not attack the colored images already formed.

The developers which we use are so-called color-forming developers, such as are well known in the art. These developers produce an insoluble colored image associated with a silver image. Such developers giving a fairly wide range of colors have previously been described.

An example of an oxidizing bath which converts developed silver to an inert form and de-A stroys any remaining latent image is a solution containing ammonium bromide and iodine. An oxidizing bath that removes developed silver and destroys remaining latent image is a solution containing ammonium hydroxide and potassium ferricyanide.

Our invention is applicable to the making of twoor three-color subtractive prints, and under certain circumstances may be extended tothe making of more than three colors in-one layer. While our invention is not limitedby the examples given, it is fully illustrated byythefollowing method of making a two-.color subtractive print. v

Reference will be made to the accompanying drawing illustrating by a. simple iiow sheet the 85 process as carried out in a two-color process.` As the explanatory legends shown thereon indicate completely the several steps, further speciiic reference thereto is unnecessary.

Color component negatives are made in a camera in any one of the ways well known in the art. These are suitably developed and are used in the following printing operation.

A positive iilm, preferably containing a yellow dye to restrain the penetration of the printing light, is exposed from the support side through the green filter component negative. The nlm is developed about ten minutes in the following solution which gives an insoluble red image in addition to the black silver image;

Solution A Cyanaceto-phenone 1 gm.

Ethyl alcohol, 95% warm 20 cc. Ethyl chloro-acetoacetate 1 gm. 85 Sodium carbonate 10% solution 75 cc. Potassium bromide 10% solution 3 cc. p-amino-diethyl-aniline hydrochloride- 1 gm.

Water to 250 cc.

The iilm is washed in running water about iive minutes.

At this point the film contains a silver image with which is associated a dye image. It also contains undeveloped silver salts most of which are still unexposed and sensitive but a small proportion of which, even after development of the film, still have the latent image and are susceptible of development. If these remain in this condition, they will be developed in a succeeding operation with grains which are exposed under another color component image, and the color of the first image will thereby be degraded.

We have found that at this point the iilm may be submitted to an oxidizing bath which will not only remove the silver or convert it to an imagel of a silver salt not spontaneously developable, but will also destroy the latent image. Such a bath also tends strongly to reduce the sensitivity of undeveloped salts, presumably because of its tendency to be retained by the photographic emulsion. The term oxidizing bath is here used in the customary broad sense 'Ihe removal of such residual substances in a clearing bath is included in the terms "chemically sensitizing.

The silver image is converted to one of silver iodide by about four minutes treatment in the following solution.

Solution B Ammonium bromide Iodine 0.5 grams Water to 500 cc.

The lm is again washed about five minutes.

The film now carries a dye image, a corresponding silver iodide image and the residual unexposed silver salts. The bleaching or conversion baths leave residual substances that decrease the sensitivity of the silver salts. They also destroy any undeveloped latent images.

The unexposed silver bromide is submitted to a clearing bath which restores the sensitivity. as by bathing the fllm in a 1/% solution of sodium sulphite for about four minutes, after which the surplus solutionis removed by wiping or blowing.

The film may now be dried.

The film is next exposed from the emulsion side through and in register with the red filter component negative.

The film is developed about ten minutes in the following solution, which gives an insoluble bluish-green image in addition to the black silver image.

24 grams ning water.

If only two color components are used, the silver images produced as a result of the second development are now removed or bleached by a silver solvent which does not attack the color images. Such solvents are well known in the art. Examples are Farmers reducer, a solution of potassium ferricyanide and potassium bromide followed by sodium thiosulfate, or a solution containing potassium ferricyanide and ammonium hydroxide. A preferred method is to treat the film with the following:

Solution D l Potassium ferricyande 5 grams Potassium bromide 'i 5 grams Water to 250 cc.

After bathing the film for a given time in Solution D, the film is rinsed and is then fixed in a 30% solution of plain sodium thiosulfate which removes the remaining undeveloped salts and also the silver iodide.

Finally, the lrn is washed and dried.

The compositions of the various solutions, used, including the developers, do not form any part of the present invention.

The bleaching and clearing steps may be omitted but the results are not so satisfactory as regards color rendering. In this case the silver remains in the film and all the silver images are removed at one time following the last development.

While we have illustrated the invention with a two-color process, it is understood that a similar procedure could be followed for a threeor even a four-color process. In such a case, the second development will be followed by the oxidizing bath constituting our improved step and all the silver and silver salt images remaining after the last development will be removed at that time. It will be further evident to those skilled in the art that a number of variations are possible in the various stages.

We consider as included in our invention all modifications, variations and equivalents coming Within the scope of the appended claims.

What we claim is:

1. The process of color photography comprising exposing a sensitive element to a color component image, developing the element in a developer forming a silver image and adye image associated therewith, removing the silver image, there exposing the element to another color component image and again developing the element in a developer forming a silver image and a dye image differently colored from the first and removing the second silver image.

2. A color process comprising exposure of a single gelatine silver halide layer to a color separation negative', developing the resultant image with a color-forming developer which yields a silver and dye image, submitting the layer to the action of an oxdizing agent that converts the silver into a silver salt not susceptible' to development Without re-exposure and destroys any remaining latent image, again exposing the layer to a different colorl separation negative and developing the resultant image with a different color forming developer yielding a silver and dye image, the last named dye image being of contrasting color to the first, and removing the last named silver image with a reagent that does not affect the dye images.

3. A color process comprising exposure of a single gelatine silver halide layer to a color separation negative, developing the resultant image with a color-forming developer which yields a silver and dye image, submitting the layer to the action of an oxidizing agent that converts the silver into a silver salt not susceptible to development without re-exposure and destroys any remaining latent image, chemically resensitizing the layer, again exposing the layer to a, different color separation negative and developing the resultant image with a different color forming developer yielding a silver and dye image, the last named dye image being of contrasting color to the first, and 130 removing the last named silver image with a reagent that does not affect the dye images.

4. A color process4 comprising exposure of a single gelatine silver halide layer to a color separation negative, developing the resultant image 185 with a color-forming developer yielding a silver and dye image, converting the silver image into silver iodide, again exposing the layer to a different color separation negative and developing the I resultant image with a different color developer yielding a silver and dye image of different color from the first and then removing the last named silver image in a reagent that does not affect the dye images.

5. A color process comprising exposure of.a single gelatine silver halide layer to a color separation negative, developing the resultant image with a color-forming developer yielding a silver and dye image, converting the silver image into a silver iodide, chemically resensitizing the layer, again exposing the layer to a different color separation negative and developing the resultant image with a different color developer yielding a silver and dye image of dierent color from the rst and then removing the last named silver image in a reagent that does not affect the dye images.

6. A color process comprising exposure of a single gelatine silver halide layer to a color separation negative, developing the resultant image with a color-forming developer yielding a silver and dye image, converting the silver image into silver iodide, chemically resensitizing the layer, again exposing the layer to a different color separation negative and developing the resultant image with a different color developer yielding a silver and dye image of different color from the first and then removing the last namedsilver image in a reagent that does not affect the dye images and removing all the remaining silver salts.

'7. The process of producing a plurality of colored images in a single photographic emulsion layer which comprises making a corresponding number of color separation-negatives, exposing a positive film to one of said color separation negatives, developing the positive image with a colorforming developer that gives a product complementary in color to that of the iilter used in making said color separation negative, submitting the film to the action of an oxidizing agent that converts the developed silver into a salt of silver which is not susceptible to development Without further exposure to light and destroys any remaining latent image, making additional separate exposures through the other color separation negatives, each time before the next exposure developing in a color-forming developer that gives a product complementary in color to that of the corresponding filter and submitting the developed layer to the action of an oxidizing agent that converts the developed silver into a salt of silver which is not susceptible to development Without further exposure to light, removing the silver formed with a reagent that does not aiiect the colored images, and xing out the remaining silver salt.

8. The process of producing a plurality of col-- ored images in a single photographic emulsion layer which comprises making a corresponding number of color separation negatives; exposing a positive lm to one of said color separation negatives; developing the positive image withl a colorforming developer that gives a product complementary in color to that of the filter used in making said color separation negative; submitting the lm to the action of an oxidizing agent that converts the developed silver into a salt of silver which is not susceptible to development Without further exposure to light and destroys any remaining latent image; making additional separate exposures through the other color separation negatives, each time before the next exposure chemically resensitizing the layer, developing in a color-forming developer that gives a product complementary in color to that of the corresponding filter and submitting the developed layer to the action of an oxidizing agent that converts the developed silver into a salt of silver which is not susceptible to development without further exposure to light; removing the silver formed with a reagent that does not affect the colored images; and fixing out the remaining silver salt.

9. The process of producing three colored images in a single photographic emulsion layer which comprises making three colorseparation negatives through tri-color filters, exposing a positive film through-one of said color separation negatives, developing the positive image with a color-forming developer which gives a product complementary in color to that of the filter used in making said color separation negative, submitting the layer to the action of an oxidizing agent that converts the developed silver to a salt of silver which is not susceptible to development without further exposure to light, making a second exposure through another of the color separation negatives, developing the second exposure in a color-forming developer that gives a product complementary in color to that of the lter used in taking said other color separation negative, submitting the layer to the action of an oxidizing agent which converts developed silver into' a salt of silver which is not susceptible to development without further exposure to light, making a third exposure through the third of said three color separation negatives, developing in a color-forming developer yielding a color complementary to that of the filter used in making said third color separation negative, removing the silver formed with a reagent that does not aiect the colored images, and fixing out remaining silver salt.

10. The process of producing two colored images in a single photographic emulsion layer which comprises making two color separation negatives through complementary lters, exposing a positive film through one of said color separation negatives, developing the positive image with a color-forming developer that gives a product complementary in color to that of the filter used in making said color separation negative, submitting the layer to the action of an oxidizing bath that converts the developed silver to a salt of silver which is not susceptible to development without further exposure to light and destroys any remaining latent image, making a second exposure through the other color separation negative, developing the second exposure in a colorforming developer that gives a product complementary in color to that of the filter used in taking said other color separation negative, removing the silver formed with a reagent that does not affect the colored images, and fixing out remaining silver salt. l

11. The process of producing two colored images in a single photographic emulsion layer which comprises making two color separation negatives through complementary red and green iters, exposing a positive lm through the green lter component negative, developing the positive image in a color-forming developer which gives an insoluble red image in addition to the silver image, submitting the layer to an oxidizing bath which converts the silver to silver iodide and destroys any remaining latent image, chemically resensitizing the layer, exposing a second time through the red filter component negative in register with the iirst printing, developing in a color forming developer which gives an insoluble bluish green image in addition to the silver image, removing the silver formed with a reagent that does not affect the colored images, and fixing out remaining silver salt.

MERRILL W. SEYMOUR. ROBERT L. BURWELL, JR. 

